Power supply

A power supply connected to a peripheral interface of a computer, the power supply comprising:

• a direct current (DC) voltage converter connected to a voltage terminal of the peripheral interface to receive a first voltage of the peripheral interface;
• a display to display an input interface to allow a voltage value to be inputted in the input interface;
• a voltage output interface connected to the DC voltage converter;
• and
• a main controller connected to the DC voltage converter, the voltage output interface, and the display, the main controller comprising:
• a voltage obtaining module to obtain the inputted voltage value, and output the inputted voltage value;
• a control module to receive the inputted voltage value, and output a pulse width modulation (PWM) signal to the DC voltage converter according to a proportion relationship between the inputted voltage value and a predetermined voltage value stored in the control module, wherein the DC voltage converter converts the first voltage into a second voltage according to the PWM signal;
• and
• a determination module to determine whether the value of the second voltage is equal to the inputted voltage value, wherein if the value of the second voltage is equal to the inputted voltage value, the determination module outputs a control signal to the control module, wherein the control module controls the DC voltage converter to output the second voltage through the voltage output interface, and controls the display to display the value of the second voltage;
• if the value of the second voltage value is not equal to the inputted voltage value, the determination module transmits an instruction to the control module;
• wherein the control module adjusts a duty cycle of the PWM signal according to the instruction, and outputs the adjusted PWM signal to the DC voltage converter to make the value of the second voltage equal to the input voltage value.